Muscular System Flashcards

1
Q

Types of Muscle Tissue

A
  1. Skeletal muscle
  2. Cardiac muscle
  3. Smooth muscle
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2
Q

elongated muscle cells eg. Skeletal and smooth muscle
cells

A

Muscle fibers

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3
Q

both are word roots meaning “muscle”

A

Myo or mys

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4
Q

meaning flesh

A

sarco

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5
Q

attach to and cover the bony skeleton

A

Skeletal Muscle

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6
Q

the longest muscle cells and have obvious stripes called

A

striations

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7
Q

the longest muscle cells

A

Skeletal Muscle

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8
Q

the longest muscle cells and have obvious stripes called striations

A

Skeletal Muscle

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9
Q

Skeletal muscle is a ________________ because it is subject to
conscious contro

A

voluntary muscle

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10
Q

responsible for overall body mobility

A

Skeletal Muscle

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11
Q

tires easily and must rest after short periods of activity

A

Skeletal Muscle

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12
Q

occurs only in the heart

A

Cardiac Muscle

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13
Q

cardiac muscle cells are

A

striated

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14
Q

is cardiac muscle voluntary or involuntary?

A

involuntary muscle

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15
Q

contracts at a fairly steady rate set by the heart’s pacemaker

A

Cardiac Muscle

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16
Q

found in the walls of hollow visceral organs, such as the stomach, urinary bladder, and respiratory passages

A

Smooth Muscle

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17
Q

Smooth Muscle is found in the walls of hollow visceral organs, such as the

A

stomach, urinary bladder, and respiratory passages

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18
Q

Special Characteristics of Muscle Tissue

A

Excitability, Contractility, Extensibility, Elasticity

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19
Q

capacity of muscle to respond to a stimulus

A

Excitability

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20
Q

ability of a muscle to shorten and generate pulling force

A

Contractility

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21
Q

muscle can be stretched back to its original length

A

Extensibility

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22
Q

ability of muscle to recoil to original resting length after stretched

A

Elasticity

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23
Q

Muscle Functions

A
  • Body movement (Locomotion)
  • Maintenance of posture
  • Respiration
  • Communication (Verbal and Facial)
  • Constriction of organs and vessels
  • Heart beat
  • Production of body heat (Thermogenesis)
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24
Q

stimulate muscle fibers to contract

A

Motor neurons

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25
Q

neuron axons branch so that each muscle fiber (muscle
cell) is innervated

A

Motor neurons

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26
Q

form a neuromuscular junction

A

Motor neurons

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27
Q

neuromuscular junction =

A

myoneural junction

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28
Q

muscles require large amounts of energy

A

Capillary beds surround muscle fibers

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29
Q

extensive vascular network delivers necessary oxygen and nutrients and carries away metabolic waste produced by muscle fibers

A

Capillary beds surround muscle fibers

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30
Q

Dense regular connective tissue surrounding entire muscle

A

Epimysium

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31
Q

Separates muscle from surrounding tissues and organs

A

Epimysium

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32
Q

Connected to the deep fascia

A

Epimysium

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33
Q

Epimysium is connected to the

A

deep fascia

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34
Q

Collagen and elastic fibers surrounding a group of muscle fibers called a fascicle

A

Perimysium

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35
Q

Collagen and elastic fibers surrounding a group of muscle fibers called a

A

fascicle

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36
Q

Loose connective tissue that surrounds individual muscle fibers

A

Endomysium

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37
Q

Endomysium contains

A

blood vessels, nerves and satellite cells

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38
Q

embryonic stem cells function in repair of muscle tissue

A

satellite cells

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39
Q

Collagen fibers of all 3 layers come together at each end of muscle to form a

A

tendon or aponeurosis

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40
Q

consists of hundreds to thousands of muscle cells, plus connective tissue wrappings, blood vessels, and nerve fibers.

A

Muscle (organ)

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41
Q

Connective Tissue Wrappings of Muscle (organ)

A

covered externally by the epimysium

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42
Q

is a discrete bundle of muscle cells, segregated from the rest of the muscle by a connective tissue sheath

A

Fascicle

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43
Q

a portion of muscle

A

fascicle

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44
Q

Connective Tissue Wrappings of Fascicle

A

surrounded by perimysium

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45
Q

is an elongated multinucleate cell

A

Muscle Fiber (cell)

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46
Q

it has a banded (striated) appearance

A

Muscle Fiber (cell)

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47
Q

Connective Tissue Wrappings of Muscle Fiber (cell)

A

surrounded by endomysium

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48
Q

Skeletal muscles span joints and attach to bones (or other structures) in at least two places:

A

Insertion and Origin

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49
Q

the movable bone when a muscle contracts

A

Insertion

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50
Q

immovable or less movable bone where the movable bone moves towards

A

Origin

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51
Q

cell membrane

A

Sarcolemma

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52
Q

Surrounds the sarcoplasm

A

Sarcolemma

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53
Q

cytoplasm of fiber

A

sarcoplasm

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54
Q

Contains many of the same organelles seen in other cells

A

Sarcolemma

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55
Q

Has an abundance of the oxygen-binding protein myoglobin

A

Sarcolemma

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56
Q

oxygen-binding protein

A

myoglobin

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57
Q

Punctuated by openings called the transverse tubules (Ttubules)

A

Sarcolemma

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58
Q

Carcolemma is punctuated by openings called the

A

transverse tubules (T-tubules)

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59
Q

Narrow tubes that extend into the sarcoplasm at right angles to the surface

A

Transverse tubules (T-tubules)

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60
Q

Filled with extracellular fluid

A

Transverse tubules (T-tubules)

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61
Q

cylindrical structures within muscle fiber

A

Myofibrils

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62
Q

Are bundles of protein filaments

A

Myofibrils

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63
Q

protein filaments

A

myofilaments

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64
Q

Two types of myofilaments

A
  1. Actin filaments (thin filaments)
  2. Myosin filaments (thick filaments)
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65
Q

At each end of the fiber, ________________ are anchored to the inner surface of the sarcolemma

A

myofibrils

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66
Q

When myofibril _________________, muscle ______________

A

shortens; shortens

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67
Q

a segment of a myofibril

A

Sarcomere

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68
Q

is the contractile unit

A

Sarcomere

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69
Q

composed of myofilaments made up of contractile proteins

A

Sarcomere

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70
Q

Extended macromolecular structure

A

Myofilament or filament

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71
Q

Two types of Myofilament or filament

A

thick filament and thin filament

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72
Q

Contain bundled myosin molecules

A

thick filaments

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73
Q

Consists of many myosin molecules whose heads protrude at opposite ends of the filament

A

thick filaments

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74
Q

Contain actin molecules (plus other proteins)

A

thin filaments

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75
Q

Consists of two strands of actin subunits twisted into a helix plus two types of regulatory proteins

A

thin filaments

76
Q

thin filaments consists of two strands of actin subunits twisted into a helix plus two types of regulatory proteins which are

A

troponin and tropomyosin

77
Q

The sliding of the thin filaments past the thick filaments

A

Muscle shortening

78
Q

Maintain the organization of the A band

A

Elastic Filaments

79
Q

Provide elastic recoil when muscle contraction ends

A

Elastic Filaments

80
Q

a dark band

A

A bands

81
Q

full length of thick (myosin) filament

A

A bands

82
Q

protein to which myosins attach

A

M line

83
Q

has thick but NO thin filaments

A

H zone

84
Q

a light band

A

I bands

85
Q

from Z disks to ends of thick filaments

A

I bands

86
Q

has thin but NO thick filaments

A

I bands

87
Q

Extends from A band of one sarcomere to A band of the next sarcomere

A

I bands

88
Q

filamentous network of protein

A

Z disk

89
Q

Serves as attachment for actin myofilaments

A

Z disk

90
Q

elastic chains of amino acids

A

Titin filaments

91
Q

keep thick and thin filaments in proper alignment

A

Titin filaments

92
Q

is an elaborate, smooth endoplasmic reticulum

A

Sarcoplasmic Reticulum

93
Q

runs longitudinally and surrounds each myofibril

A

Sarcoplasmic Reticulum

94
Q

Form chambers called terminal cisternae on either side of the T-tubules

A

Sarcoplasmic Reticulum

95
Q

Chambers formed by sarcoplasmic reticulum on either side of the T-tubules

A

terminal cisternae

96
Q

stores Ca++ when muscle not contracting

A

Sarcoplasmic Reticulum

97
Q

when stimulated, calcium released into sarcoplasm

A

Sarcoplasmic Reticulum

98
Q

Sarcoplasmic Reticulum release ______________ into sarcoplasm when stimulated

A

calcium

99
Q

has Ca++ pumps that function to pump Ca++ out of the sarcoplasm back into the SR after contraction

A

Sarcoplasmic Reticulum Membrane

100
Q

Formed by a single T-tubule and the 2 terminal cisternae

A

triad

101
Q

run near the aligned A- and I-band boundaries of sarcomeres

A

T-tubules

102
Q

In a relaxed muscle fiber, the thin and thick filaments overlap only at the ends of the ___________________

A

A band

103
Q

When the muscle shortens:

A
  1. The I-bands shorten
  2. the distance between successive Z discs shortens
  3. the H zones disappear
  4. the contiguous A bands move closer together but their length does not change
104
Q

Events before the muscle fiber contraction

A
  1. The fiber must be activated, that is, stimulated by a nerve ending so that a change in membrane potential occurs.
  2. Next, it must generate an electrical current, called an action potential, in its sarcolemma.
  3. The action potential is automatically propagated along the sarcolemma.
  4. Then, intracellular calcium ion levels must rise briefly, providing the final trigger for contraction.
105
Q

The Nerve Stimulus and Events at the Neuromuscular Junction

A
  1. When a nerve impulse reaches the end of an axon, the axon terminal releases ACh into the synaptic cleft.
  2. ACh diffuses across the cleft and attaches to ACh receptors on the sarcolemma of the muscle fiber.
  3. ACh binding triggers electrical events that ultimately generate an action potential.
106
Q

After ACh binds to the ACh receptors, its effects are quickly terminated by

A

acetylcholinesterase

107
Q

breaks down ACh to its building blocks, acetic acid and choline

A

acetylcholinesterase

108
Q

Involves a shortage of Ach receptors

A

MYASTHENIA GRAVIS

109
Q

Myasthenia Gravis is characterized by

A
  • drooping upper eyelids
  • difficulty swallowing and talking
  • generalized muscle weakness
110
Q

Autoimmune disease of Myasthenia Gravis:

A

antibodies are formed against ACh receptors

111
Q

Generation of an Action Potential Across the Sarcolemma

A
  1. An end plate potential is generated at the neuromuscular junction
  2. Depolarization: Generating and propagating an action potential (AP)
    - The local depolarization current spreads to adjacent areas of the sarcolemma. This opens voltage-gated sodium channels there, so Na+ enters following its electrochemical gradient and initiates the AP. The AP is propagated as its local depolarization wave spreads to adjacent areas of the sarcolemma, opening voltage-gated channels there. Again, Na+ diffuses into the cell following its electrochemical gradient.
  3. Repolarization: Restoring the sarcolemma to its initial polarized state (negative inside, positive outside)
    - Repolarization occurs as Na+ channels close (inactivate) and voltage-gated K+ channels open. Because K+ concentration is substantially higher inside the cell than the extracellular fluid, K+ diffuses rapidly out of the muscle fiber.
112
Q

the sequence of events by which transmission of an action potential along the sarcolemma causes myofilaments to slide

A

Excitation-Contraction Coupling

113
Q

Excitation-Contraction Coupling

A
  1. The action potential (AP) propagates along the sarcolemma and down the T-tubules
  2. Calcium ions are released.
    - Transmission of the AP along the T tubules of the triads causes the voltage-sensitive tubule proteins to change shape. This shape change opens the Ca2+ release channels in the terminal cisterns of the sarcoplasmic reticulum (SR), allowing Ca2+ to flow into the cytosol.
  3. Calcium binds to troponin and removes the blocking action of tropomyosin.
    - When Ca2+ binds, troponin changes shape, exposing binding sites for myosin (active sites) on the thin filaments.
  4. Contraction begins:
    - Myosin binding to actin forms cross bridges and contraction (cross bridge cycling) begins. At this point, E-C coupling is over.
114
Q

Is the series of during which myosin heads pull thin filaments toward the center of the sarcomere.

A

Cross Bridge Cycling

115
Q

Cross Bridge Cycling

A
  1. Cross bridge formation.
    - Energized myosin head attaches to an actin myofilament, forming a cross bridge.
  2. The power (working) stroke.
    - ADP and Pi are released and the myosin head pivots and bends, changing to its bent low-energy state. As a result, it pulls the actin filament toward the M line.
  3. Cross bridge detachment.
    - After ATP attaches to myosin, the link between myosin and actin weakens, and the myosin head detaches (the cross bridge “breaks”).
  4. Cocking of the myosin head.
    - As ATP is hydrolyzed to ADP and Pi, the myosin head returns to its prestrike high-energy, or “cocked,” position.
116
Q

Types of Muscle Contraction

A
  • Isotonic contraction (concentric)
  • Isometric contraction
117
Q

On stimulation, muscle develops enough tension (force) to lift the load (weight). Once the resistance is overcome, the muscle shortens, and the tension remains constant for the rest of the contraction.

A

Isotonic contraction (concentric)

118
Q

Two types of Isotonic contraction (concentric)

A

Concentric contractions and Eccentric contractions

119
Q

muscle shortens and does work

A

Concentric contractions

120
Q

muscle generates force as it lengthens

A

Eccentric contractions

121
Q

occur when a muscle attempts to move a load that is greater than the force (tension) the muscle is able to develop.

A

Isometric contraction

122
Q

Muscle is attached to a weight that exceeds the muscle’s peak tension-developing capabilities. When stimulated, the tension increases to the muscle’s peak tension-developing capability, but the muscle does not shorten.

A

Isometric contraction

123
Q

Pathways for regenerating ATP during muscle activity:

A
  • Direct phosphorylation
  • Anaerobic pathway
  • Aerobic pathway
124
Q

Coupled reaction of creatine phosphate (CP) and ADP

A

Direct phosphorylation

125
Q

Energy source of Direct phosphorylation:

A

Creatine Phosphate

126
Q

Oxygen used in Direct phosphorylation:

A

None

127
Q

Products of Direct phosphorylation:

A

1 ATP per CP, creatine

128
Q

Duration of energy provided in

A

15 seconds

129
Q

Glycolysis and lactic acid formation

A

Anaerobic Pathway

130
Q

Energy source of Anaerobic Pathway:

A

Glucose

131
Q

Oxygen used in Anaerobic Pathway:

A

None

132
Q

Products of Anaerobic Pathway:

A

2 ATP per glucose, lactic acid

133
Q

Duration of energy provided in Anaerobic Pathway:

A

30-40 seconds, or slightly more

134
Q

Aerobic cellular respiration

A

Aerobic Pathway

135
Q

Energy source of Aerobic Pathway:

A

glucose; pyruvic acid; free fatty acids from adipose tissue; amino acids from protein metabolism

136
Q

Oxygen used in Aerobic Pathway:

A

Required

137
Q

Products of Aerobic Pathway:

A

32 ATP per glycose, CO2, H20

138
Q

Duration of energy provided in Aerobic Pathway:

A

Hours

139
Q

The fastest pathway is

A

Direct Phosphorylation

140
Q

The slowest pathway is

A

Aerobic Pathway/Aerobic Respiration

141
Q

Energy sources used during short-duration exercise and prolonged-duration exercise:

Short-duration exercise

6 seconds:

A

ATP is stored in muscles used first

142
Q

Energy sources used during short-duration exercise and prolonged-duration exercise:

Short-duration exercise

10 seconds:

A

ATP is formed from creatine phosphate and ADP (direct phosphorylation).

143
Q

Energy sources used during short-duration exercise and prolonged-duration exercise:

Short-duration exercise

30-40 seconds and End of Exercise:

A

Glycogen stored in muscles is broken down to glucose, which is oxidized to generate ATP (anaerobic pathway)

144
Q

Energy sources used during short-duration exercise and prolonged-duration exercise:

Prolonged-duration exercise

Hours:

A

ATP is generated by breakdown of several nutrient energy fuels by aerobic pathway.

145
Q

a state of physiological inability to contract even though the muscle still may be receiving stimuli

A

Muscle Fatigue

146
Q

Causes of Muscle Fatigue

A
  • ionic imbalances
  • accumulation of inorganic phosphate (Pi)
  • lactic acid
147
Q

raises the concentration of H+ and alters contractile proteins

A

lactic acid

148
Q

extra amount of oxygen that the body must take in for these restorative processes

A

Excess Postexercise Oxygen Consumption (EPOC)

149
Q

reason for hyperventilation during exercises

A

Excess Postexercise Oxygen Consumption (EPOC)

150
Q

For a muscle to return to its resting state, all the following must occur:

A
  1. Its oxygen reserves in myoglobin must be replenished.
  2. The accumulated lactic acid must be reconverted to pyruvic acid.
  3. Glycogen stores must be replaced.
  4. ATP and creatine phosphate reserves must be resynthesized.
151
Q

moderately weak but sustained muscle activity required for endurance exercise does not promote significant skeletal muscle hypertrophy

A

Resistance Exercise

152
Q

results mainly from high-intensity resistance exercise (eg. weight lifting or isometric exercise)

A

Muscle Hypertrophy

153
Q

degeneration and loss of mass

A

Disuse Atrophy

154
Q

begins when muscles are immobilized

A

Disuse Atrophy

155
Q

muscle strength can decline at the rate of

A

5% per day

156
Q

Thick filaments are fewer but have myosin heads along their entire length.

A

Smooth Muscle

157
Q

No troponin complex in thin filaments

A

Smooth Muscle

158
Q

a protein that acts as the calcium binding site

A

calmodulin

159
Q

In Smooth Muscle, thick and thin filaments arranged

A

diagonally

160
Q

lacks the highly structured neuromuscular junctions of skeletal muscle

A

Smooth Muscle

161
Q

dense body network (serving as the Z disk)

A

Intermediate filament

162
Q

Contraction of Smooth Muscle

A
  1. Calcium ions (Ca2+) enter the cytosol from the ECF via voltage-dependent or voltage independent Ca2+ channels, or form the scant SR.
  2. Ca2+ binds to and activates calmodulin.
  3. Activated calmodulin activates the myosin light chain kinase enzymes.
  4. The activated kinase enzymes catalyze transfer of phosphate to myosin, activating the myosin ATPases.
  5. Activated myosin forms cross bridges with actin of the thin filaments. Shortening begins
163
Q

Different autonomic nerves serving the smooth muscle of visceral organs release different neurotransmitters

A

Neural Regulation

164
Q

Neurotransmitters

A
  • acetylcholine
  • norepinephrine
  • gastrin
165
Q

smooth muscle location of acetylcholine

A

bronchioles

166
Q

action of acetylcholine

A

strong contraction that narrows the bronchioles

167
Q

smooth muscle location of norepinephrine

A

bronchioles and blood vessels

168
Q

action of norepinephrine

A

dilates the bronchioles, constriction

169
Q

Hormones and Local Chemical Factors

A
  • Histamine
  • excess carbon dioxide
  • low pH
  • lack of oxygen
170
Q

smooth muscle location of gastrin

A

stomach

171
Q

action of gastrin

A

contract, to churn food

172
Q

Types of Smooth Muscle

A
  • Unitary Smooth Muscle
  • Multiunit Smooth Muscle
173
Q

Unitary Smooth Muscle is found in

A

walls of all hollow organs except the heart

174
Q

are arranged in opposing (longitudinal and circular) sheets

A

Unitary Smooth Muscle

175
Q

Are innervated by varicosities of autonomic nerve fibers

A

Unitary Smooth Muscle

176
Q

Unitary Smooth Muscle are innervated by varicosities of

A

autonomic nerve fibers

177
Q

often exhibit rhythmic spontaneous action potentials

A

Unitary Smooth Muscle

178
Q

Unitary Smooth Muscle are electrically coupled by

A

gap junctions

179
Q

are electrically coupled by gap junctions and so contract as a unit (for this reason recruitment is not an option)

A

Unitary Smooth Muscle

180
Q

Respond to various chemical stimuli

A

Unitary Smooth Muscle

181
Q

Electrical isolation of cells allows finer motor control

A

Unitary Smooth Muscle

182
Q

smooth muscles in the large airways to the lungs and in large arteries, the arrector pili muscles attached to hair follicles, and the internal eye muscles that adjust pupil size and allow the eye to focus visually

A

Multiunit Smooth Muscle

183
Q

Consists of muscle fibers that are structurally independent of one another

A

Multiunit Smooth Muscle

184
Q

Is richly supplied with nerve endings, each of which forms a motor unit with a number of muscle fibers

A

Multiunit Smooth Muscle

185
Q

Responds to neural stimulation with graded contractions that involve recruitment

A

Multiunit Smooth Muscle

186
Q

Gap junctions permit coordinated contraction

A

Multiunit Smooth Muscle